Will Climate Change Affect Water Supply on the Missouri River?

How climate change will affect water supply from the Missouri River is not yet known. Current problems with Missouri River water supply principally affect the barge transportation industry, and the agricultural and industrial clients that use it to transport their goods and supplies.

The Missouri River is important for Missouri. More than half of Missouri residents get their drinking water from the Missouri River or the alluvial aquifer it directly feeds. Not only that, the river’s water is used for agricultural irrigation, for industry, to support barge traffic along the Missouri and Mississippi Rivers, for recreation, and to support the ecosystems that depend on the river for their survival.

Figure 1. Dams and Other Locations Along the Missouri River. Source: Google Earth.

In the previous post, I reported that the snowpack in the western United States has declined by 23%, and it is forecast to decline more by 2038. The eastern border of the study area forms the western boundary of the Missouri River Basin. Will the changing western snowpack impact the Missouri River’s ability to supply Missouri’s needs?

The answer is complicated. Precipitation in the Upper Missouri River Basin has historically fallen mostly as snow, building a winter snowpack that slowly melts during the spring. The snowmelt is gathered into reservoirs created by 6 large dams along the Missouri River, plus more than 40 smaller ones on tributaries. The 6 large dams begin at the Gavin’s Point Dam on the Nebraska-South Dakota border, and extend upriver to the Ft. Peck Dam in Montana. (See Figure 1.) The result is that water flow below the reservoirs is largely controlled by man, not nature.

Figure 2. Data source: Wikipedia.

The annual water yield from the Missouri River is small compared to the size of its basin. The data is given in Figure 2, where the red columns represent the length of the rivers, and the blue line represents their average discharge. No other river in the USA serves such a large basin with so little water. In drought years it is already too small to fully meet all of the demands that are put on it, resulting in conflict over how to manage the river, and over which values to give priority. The conflict has primarily been between up-river interests, which would like to see water allocated to support irrigation, drinking water, and mitigation in their states during periods of drought, and down-river interests, which would like to see water released to support commercial navigation on the river.



Figure 3. Source: Hansen Professional Services, Inc. 2011.

In 2004, the Army Corps of Engineers changed the rules by which the river is operated to reduce water releases during drought. During drought years, this better supports up-stream interests, but results in a shorter season during which the river can support barge traffic. The result has been a decrease in annual tonnage moved on the river (Figure 3).







Figure 4. Well Drilling in Western North Dakota. Source: Vanosdall 2013.

In addition, development in the Upper Missouri Basin has increased water demand in that region. A prime example would be the development of the oil and gas reserves in North Dakota. Well drilling uses large quantities of water. (See Figure 4). Given that the water yield from the Missouri River is already too small to fully support all of the demands placed on it, any increase in demand is bound to constrain supply even further.

The constraints discussed above, however, are all man-made constraints. How will climate change and the declining western snowpack affect all of this?





Source: National Centers for Environmental Information.

The snowpack decline has occurred because of increasing temperature, not decreasing precipitation. Figures 5 repeats a chart I published in January 2016, showing that precipitation has increased in the region over time.







Figure 6. Source: Melillo 2014.

Figure 6 shows that the 2011 National Climate Assessment projects that the annual flow on the Missouri River will actually increase by about 15% by 2070. However, more precipitation will fall as rain instead of snow, and the snow that does fall will melt sooner. This means that more water will enter the reservoirs during winter and early spring, and less during late spring and summer. In addition, increased temperature will increase evaporation from the river and reservoirs, and it will increase water consumption by crops, leading to earlier and increased demand for water. There is a potential mismatch between when the water is available and when it is needed.

The question will be whether it will be possible to manage the reservoirs successfully under the new conditions. When looking at the water situation in California (here), we discovered that water authorities expected climate change to create reservoir management problems that would result in an increased water deficit during the summer and autumn. It is possible that the reservoirs along the Missouri will encounter similar problems, but it is not certain.

One potential difference is that California has multiple, relatively short rivers, leading to only one large reservoir per river, and perhaps one or two small feeder reservoirs. The Missouri River, however, is a single long river. It has 6 large reservoirs chained along it, plus at least 40 feeder reservoirs on tributaries. This may give managers flexibility in managing the river that is not possible in California.

Five separate water resource studies have been undertaken to determine how climate change will impact the ability of the Missouri River to meet the demands placed on it. Unfortunately, they have not all been completed, and I can find no comprehensive analysis.

For the time being, problems with water supply on the Missouri River involve human decisions about how to manage the river. To date, in the State of Missouri they have primarily impacted the barge industry, plus the farmers and industries that depend on the barge industry to transport their goods and supplies.


Drew, John, and Karen Rouse. 2006. “Missouri Water in High Demand.” Missouri Resources, Winter, 2006. Downloaded 5/31/2017 from

Bureau of Reclamation. 2016. Basin Report: Missouri River. Downloaded 5/25/2017 from

Bureau of Reclamation. 2016. SECURE Water Act Section 9503(c) – Reclamation Climate Change and Water. Prepared for United States Congress. Denver, CO: Bureau of Reclamation, Policy and Administration. Downloaded 5/25/2017 from

Hanson Professional Services, Inc. 2011. Missouri River Historic Timeline and Navigation Service Cycle. Missouri River Freight Corridor Assessment and Development Plan. Downloaded 5/31/2017 from

Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W. Yohe, Eds., 2014: Climate Change Impacts in the United States: The Third National Climate Assessment. U.S. Global Change Research Program, 841 pp. doi:10.7930/J0Z31WJ2. Available online at

Vanosdall, Tiffany. 2013. Missouri River Water Supply. US Army Corps of Engineers. Downloaded 6/1/2017 from

Wikipedia. List of U.S. Rivers by Discharge. Data retrieved online 5/31/2017 at

Declining Snowpack in the American West

The snowpack over the western United States has declined about 23% since 1981. It is projected to decline more in the future.

I have written a number of posts about the looming water deficit in California due to a projected decline in the snowpack on the Sierra Nevada mountains. Is something similar projected to occur throughout the entire western United States?

Figure 1. Change in Snow Water Equivalent at SNOTEL Stations, 1955-2016. Source: Mote and Sharp 2016, in Environmental Protection Agency, 2016.

Yes. Studies find that the water content of the snowpack throughout the West has already declined 23%, and it is expected to decline more, perhaps up to 30% by 2038.

This decline is not occurring via a decrease in precipitation. Indeed, to date precipitation across the West has actually increased slightly. The decline is occurring due to increased temperature. Some precipitation that used to fall as snow now falls as rain, and the snow that does fall melts more quickly.

Mote and Sharp studied the snow water equivalent* of the snowpack in April from 1955-2016 at SNOWTEL measuring stations operated by the U.S. Natural Resource Conservation Service. Figure 1 shows a map of the stations, with blue dots representing stations where the snowpack increased and orange dots representing stations where the snowpack declined. The size of the dots represent the magnitude of change.

It is easy to see that the vast majority showed declines in the snowpack, in many cases by as much as 80%. Overall, Mote and Sharp computed that there had been an average 23% decline in the western snowpack since 1955.


Figure 2. Observed and Modeled Change in Snowpack. Source: Fyfe, et al, 2017.

Fyfe and his colleagues conducted climate modeling to try to determine whether the decline in the snowpack was due to natural causes or human causes. Figure 2 shows the results in a rather complicated graph. Let’s unpack it. The computer models ran from 1950 to 2010. The dashed black line shows the observed trend in the snow water content. The solid blue line shows the projected snow water content if only natural climate causes are included in the model. It doesn’t fit the observed trend very well. The solid black line shows the projected snow water content if both natural and human climate causes are included in the model. It fits the observed data quite closely. (The pink and green lines show data from analyses using other sets of data and need not concern us here. The gray band and blue dotted lines show statistical confidence levels for the computer simulations, and also need not concern us here.)

The simulation that included both natural and human causes agreed with the observed data, but the one that included only natural causes did not. The authors concluded that natural causes could not explain the loss of snowpack in the West. A combination of human and natural causes could explain it.

Figure 3. Projected Short-Term Change in Snowpack. Source: Fyfe, et al, 2017.

Fyfe and his colleagues also conducted a suite of climate models to project snowpack loss into the future. The results are shown in Figure 3. In this graph, the y-axis represents the actual snow water content of the snowpack, not the change. The blue line represents the computer model that projected the least snowpack loss in 2030, and the red line represents the computer model that projected the most loss. It is common practice among climate modelers to run a suite of projections, and when this is done, the average of them is often also presented, and it is often taken as likely to be the most accurate. In Figure 3, the average of the projections is represented by the black line.

It is easy to see that the trend in all of the lines is down. There is considerable variation from point-to-point in the red and blue lines, indicating that the projections expect there to be considerable variability in the snowpack from year-to-year. The black line is pretty smooth, however, as might be expected from an average of several analyses, and it has a consistent downward trend. The losses in snowpack in some of the projections ran as high as 60%, though average loss across the suite of projections was about 30%.

A 30% decline in the snowpack does not sound so dire; after all the projections are for a 60% loss of snowpack in California (see here). However, that projection was for the end of the century. This projection is for 2038; that’s only 20 years from now.

Some may wonder about how little snow water equivalent is shown on the y-axis of Figure 3. In the 1990s, the snowpack maxed-out each year at only 6+ cm. of snow water equivalent. In thinking about this number, remember two things: first, a centimeter of water represents somewhere between 3 and 20 centimeters of snow, with an average value being somewhere around 10 cm. Thus, 6 cm. of snow water equivalent would roughly equal 60 cm. of snow, or 23.6 inches. Thus, the average depth of the snowpack was about 2 feet. Second, remember that the measurements were averaged across hundreds of locations; some were high and received a great deal of snow, but some were relatively low (low altitude means more rain, less snow), or were located in areas that don’t receive much precipitation of any kind.

Much of Missouri depends on the Missouri River as a water supply, including both Kansas City and St. Louis. The Missouri River gets much of its water from the western snowpack. A declining snowpack may, or may not, have implications for our water supply, depending on whether the reservoirs along the Missouri River can accommodate the shift toward earlier snowmelt and increased rain. I will look at this issue in the next post.

*   Snow water equivalent: Different types of snow hold different amounts of water. Thus, scientists don’t just measure how deep the snow is. Rather, at a given location they take a representative sample of the snowpack and melt it, thereby determining how much water it holds. This is the snowpack’s snow water equivalent at that given location. April is generally when the snowpack is at its maximum.


Environmental Protection Agency. 2016. Climate Change Indicators in the United States: Snowpack. Retrieved online 5/22/2017 at

Fyfe, John, Chris Kerksen, Lawrence Mudryk, Gregory Flato, Benjamin Santer, Neil Swart, Noah Molotch, Xuebin Zhang, Hui Wan, Vivek Arora, John Scinocca, and Yanjun Jiao. 2017. “Large Near-Term Projected Snowpack Loss Over the Western United States.” Nature Communications, DOI: 10.1038/ncomms14996. Retrieved online 5/14/2017 at

Missouri Burden of Disease

In the last two posts I looked at a report that attempted to quantify the burden of disease attributable to environmental factors. It was produced by the World Health Organization (WHO), and its analysis concerned the whole earth.

The Missouri Department of Health and Senior Services produced a report on the burden of chronic diseases in Missouri in 2013. The report makes interesting reading, though it is not equivalent to the WHO report.

Figure 1. Source: Yun et al, 2013.

Of the top 8 causes of death in Missouri during 2010, 7 were chronic diseases. (Figure 1) Together, they caused 68.2% of all deaths in Missouri. Heart disease and cancer caused by far the most, between them accounting for almost half of all deaths.







Figure 2. Source: Yun et al, 2013.

If one defines premature death as death occurring before age 65, then 14,827 Missourian’s died prematurely in 2010. As shown in Figure 2, chronic diseases caused 58.4% of the deaths, cancer and heart disease again leading the way, causing 46% of all premature deaths.







Figure 3. Source: Yun et al, 2013.

Almost 3 in 4 Missourians (74.4%) were affected by at least one of 13 major chronic conditions, as shown in Figure 3 (individuals may be affected by more than one condition, thus the percentages do not sum to 100%). More than 1/3 of Missourians were living with cholesterol and hypertension, conditions which are not fatal in themselves, but which contribute to many other diseases that are. The prevalence of each of these conditions was higher in Missouri than nationally, except for vision impairment, which occurred in Missouri about at the same rate that it does nationally.

The mortality rates for heart disease, cancer, stroke, and diabetes all declined significantly in Missouri between 2000 and 2009. Prevalence rates did not, however, and for some chronic diseases prevalence rates actually increased. Thus, it seems that Missouri has made progress managing chronic diseases, but not preventing them.

The Missouri report did not address environmental factors that cause disease. To the extent that the report did consider risk factors, it focused on demographic characteristics, personal habits, and the social environment, such as the availability of health care, the availability of healthy food, and second-hand smoke. While some of these overlap with the WHO report to a limited degree, the Missouri report did not consider ecological factors such as air pollution and exposure to toxic chemicals. Despite the fact that ecological factors contribute strongly and obviously to several of the chronic conditions from which Missourians suffer, such as cancer and chronic lower respiratory disease, I could find no report addressing the issue in Missouri. If any of you know of one, please let me know.


Yun S, Kayani N, Homan S, Li J, Pashi A, McBride D, Wilson J. 2013. The Burden of Chronic Diseases in Missouri: Progress and Challenges. Jefferson City, MO: Missouri Department of Health and Senior Services. Downloaded 5/2/2017 from

Disease Burden Attributable to Environmental Factors

Environmental factors play a surprisingly large role in the disease burden with which humankind must cope.

Figure 1. Global Deaths and Disability-Adjusted Life Years Attributable to the Environment. Source: Prüss-Ustün et al, 2016.

In 2012, 12.6 million deaths worldwide (22.7% of all deaths) were attributable to environmental causes, as were 596 million disability-adjusted life years (DALYs) (21.8% of all DALYs)*. (Figure 1) So says a report issued in 2016 by the World Health Organization. I reviewed some of the report’s findings in the previous post. In this post, I turn to its findings regarding specific disease conditions.





Figure 2. Source: Prüss-Ustün et al, 2016.

The report authors found that 13 types of diseases or disease groups had the highest preventable disease burden from environmental risks. Figure 2 shows the raw number of DALYs attributable to environmental factors by disease group. Cardio-vascular diseases account for the largest disease burden worldwide, causing 119 million DALYs in 2012, some 60% more than unintentional injuries, the second largest category. Road injuries were counted separately from unintentional injuries, however. I suspect that road injuries are mostly unintentional (though road conditions and driving habits may sometimes argue otherwise). If you combine the two categories, then accidents account for 105 million DALY’s just slightly less than cardio-vascular diseases.


Figure 3 shows the same data, but in a different way. For each of the disease groups, it shows the percentage of total cases that can be attributed to the environment. Thus, 57% of all diarrheal diseases can be attributed to environmental causes, the highest fraction. Fifty percent of all unintentional injuries have environmental causes (I think this means that they can be attributed to unsafe conditions that could be remedied, like working in the diamond mines of the Ivory Coast).

Many of the conditions shown in Figures 1 and 2 are disease groups. Looking at specific individual conditions, the report found that fully 76% of fires and burnings could be attributed to environmental conditions, as could 73% of drownings and 57% of diarrheal diseases. The data start to sound almost like public safety or public health issues, as opposed to what we typically think of as “environmental” here in America. And perhaps, in many parts of the world, that is exactly right.

Figure 4. Recommended Actions by Disease Group. Source: Prüss-Ustün et al, 2016.

The authors make recommendations regarding which environmental interventions they thought would be most likely to significantly reduce the burden of environmentally caused disease for each of the 13 disease groups. The recommendations are shown in Figure 4. For those conditions most relevant in the United States (cardio-vascular disease and cancer) it is interesting to see that, along with second-hand smoke, household and ambient air pollution were thought to be important. I’ve discussed the progress Missouri has made in improving its ambient air quality several times, most recently here. We often ignore indoor air quality when we discuss air pollution, however. I don’t know how you would measure it across millions of buildings, but it is a very important environmental issue. If anybody knows about studies of indoor air pollution across Missouri or across the USA, please let me know.

I’ll try to bring all of this home to Missouri a little bit in the next post.

*Disability-Adjusted Life Year (DALY). Disability-adjusted life year is a measure used to estimate the number of years lost to early death, combined with the number of years lost to disability. To determine the number of years lost to death for an individual, subtract the age of death from the normal life expectancy. The result represents the number of years lost to death. For disabilities, subtract the age at which the disability occurred from normal life expectancy, then multiply the result by a “disability factor,” which represents the severity of the disability. The result represents the years lost to disability. Add the years lost to death and the years lost to disability, and you have the disability-adjusted life years (DALYs) for that individual. Do this calculation for every individual in the group, and sum the results across the group, and you have the DALYs for the group.


Prüss-Ustün, A., J. Wolf, C. Corvalán, R. Box, and M. Neira. 2016. Preventing Disease Through Health Environments: A Global Assessment of the Burden of Disease from Environmental Risks. WHO Press: Geneva. Downloaded 5/3/2017 online from

Death and Disease from the Environment

In 2012…12.6 million deaths globally, representing 23%…of all deaths, were attributable to the environment. When accounting for both death and disability, the fraction of the global burden of disease due to the environment is 22%… In children under five years, up to 26%…of all deaths could be prevented, if environmental risks were removed.

So begins the Executive Summary of Preventing Disease Through Health Environments: A Global Assessment of the Burden of Disease from Environmental Risks, a report issued by the World Health Organization (WHO). Those of us who think of the environment as the necessary support of all life on Earth may not find their claim surprising, but it is pretty dramatic: more than 1 death in every 5. Let’s look at what it means. This post will discuss some preliminaries and look at broad conceptual findings. The next post will look at specific disease burdens.

The authors looked at 133 types of diseases or injuries and found that 101 of them had significant links with the environment. They were able to quantify, at least partially, the environmental contribution for 92 of them. The 92 conditions run the gamut, including:

  • infectious diseases, such as malaria and diarrhreal diseases;
  • neonatal and nutritional conditions, like malnutrition and birth defects;
  • non-communicable diseases, like cancer or neurological disorders;
  • unintentional injuries, such as road traffic accidents or unintentional poisonings;
  • intentional injuries, such as self-harm or interpersonal violence; and
  • risk factors that contribute to non-communicable diseases of other types, but which are related to the environment, such as obesity and physical inactivity.

Figure 1. Source: Prüss-Ustün et al, 2016.

Some of these may seem controversial to an American public, seeming like personal choices. The authors contend, however, that each of them contributes to death or disease, and each of them has an identifiable link to environmental factors that are modifiable by people.

As one might expect, the fraction of deaths attributable to the environment is higher in poorer countries, lower in wealthy countries (Figure 1). There are several reasons for this. One is that wealthier nations are able to afford better environmental protections. Another is that wealthier nations have been able to transition to safer methods of doing almost everything (from transportation, to industrial processes, to cooking and home heating).

Figure 2. Percent Attributable to Environmental Causes, by Disease Type and Region. Source: Prüss-Ustün et al, 2016.

The type of disease impacted by the environment also varies by region (Figure 2). In Sub-Saharan Africa environmental factors cause a high number of per capita deaths from infectious, parasitic, neonatal, and nutritional diseases. Examples might include malaria, diarrheal diseases, and malnutrition. But in Europe, Southeast Asia, the Western Pacific, and High-Income OECD Nations, environmental factors cause high numbers of per capita deaths from non-communicable diseases. Examples might include cancer and heart disease.

Some background information may help in understanding the report’s findings. It is rare for the environment to sicken or kill somebody outright. Typically, the environment leads to some other condition that is the direct cause of illness or death. For instance, desertification may lead to famine, but starvation may be listed as the direct cause of death, not desertification. A contaminated water supply may lead to cholera, but cholera may be listed as the direct cause of death, not contaminated water. Asbestos may led to mesothelioma, but mesothelioma may be listed as the direct cause of death, not asbestos.

Figure 3. Conditions Environmentally Caused: Included and Excluded. Source: Prüss-Ustün et al, 2016.

The WHO report defines environmental risks broadly. Figure 3 shows what is included and what is excluded. Diseases that involve person-to-person interaction, or that result from personal habits and choices are excluded. Also excluded are disease vectors that exist in the environment, but which can’t readily be modified (for instance, pollen). Included are factors that most people would regard as environmentally modifiable (e.g. exposure to chemicals or air pollution). Thus, mesothelioma caused by asbestos exposure would be included, but getting the flu from somebody at work would not be.

Nobody keeps records of environmental exposure leading to death, especially in the undeveloped world. Thus, it has to be estimated. The report used several types of estimates which require the use of assumptions and/or expert opinion. Thus, be sure to keep in mind that the report represents an estimate. It is almost certain to contain errors, though it may be the best estimate available.

The next post will look at specific disease conditions, and what fraction of the disease burden can be attributed to environmental factors.


Prüss-Ustün, A., J. Wolf, C. Corvalán, R. Box, and M. Neira. 2016. Preventing Disease Through Health Environments: A Global Assessment of the Burden of Disease from Environmental Risks. WHO Press: Geneva. Downloaded 5/3/2017 online from

Human Exposure to Environmental Chemicals

From time-to-time I report on toxic chemicals in the environment, whether it be in fish we eat (here), polluted streams (here), or toxic waste sites (here). People come into contact with these chemicals by eating contaminated food, drinking contaminated water, and breathing contaminated air. I thought it might be interesting to see whether people are carrying a dangerous load of toxic chemicals in their bodies.

It turns out that the Centers for Disease Control (CDC) was also interested, and they have systematically tested samples of the population of the USA to see which environmental chemicals people are carrying in their blood and urine, and at what levels. They have published their findings in a series of reports, most recently in 2009, and they regularly update the data associated with the report, most recently in 2017.

There is some basic information you need to know in looking at this data. First, the data covers 308 environmental chemicals. There are over 80,000 chemicals registered for use in the USA, however, and the American Chemical Society database contains over 50 million unique chemical substances that have been discovered or created. Very little is known about the toxicity of many of them.

Second, once a toxic chemical enters your body, it seldom remains in the bloodstream for very long. Some chemicals are cleared from the body relatively quickly (often in urine), others migrate into the body’s tissues, where they sometimes persist for decades. Thus, toxic chemicals have two kinds of effects on the body: acute symptoms (those related to high levels in the blood), and chronic effects (which can be caused by even small amounts of some chemicals remaining in the tissues of the body). The CDC surveyed blood and urine levels. Thus, their data would bear most directly on acute symptoms, and would have less to say about long-term chronic exposure at low levels.

Third, most of the chemicals tested by the CDC exist at some level in the environment. You can find them in just about everyone. In fact, many are essential for health. For instance, too much iron in the blood is toxic, but too little can cause iron deficiency anemia.

Our chemical tests have become so sophisticated that they can find traces of chemicals that are smaller than microscopic. Thus, the fact that people carry some level of a chemical in their body is not evidence that it is toxic. Many additional factors need to be taken into account. The CDC reports are intended to provide baseline data.

Rather than get into the hundreds of tables provided in the report, I’ll just report a few headline findings from the Executive Summary:

  • Exposure to some chemicals is widespread.
    • Polybrominated diphenyl ethers (flame retardants used in a wide variety of products) were found in almost all of the subjects tested. These accumulate in the environment and in fatty tissue.
    • Bisphenol A, a component of epoxy resins and polycarbonates, was found in the urine samples of more than 90% of tested subjects.
    • Perfluoroctanoic acid, used in the manufacture of non-stick coatings in cookware, was found in “most” subjects tested.
  • Figure 1. Source: Centers for Disease Control and Prevention, 2009a.

    Because exposure to environmental chemicals is so widespread, it means that many (most?) people are carrying more than one in their body. Very little is known about how (if) they interact. Do they potentiate each other, making even low level exposure dangerous? We just don’t know.

  • Serum levels of lead in children have declined. The CDC has set the upper limit for lead in the blood of adults at 10 micrograms per deciliter. (This is not the safe level for children, but it does provide a marker against which change can be measured.) The percentage of children with a blood level greater than 10 µg./dl. has declined significantly since 1970 (Figure 1). Where once it was 88.2%, now it is 1.4%. This suggests that lead mitigation efforts have been tremendously successful. Some special populations remain at risk, however, especially children living in homes containing lead-based paint.

    Figure 2. Source: Centers for Disease Control and Prevention, 2009a.

  • For the first time, the report included data on exposure to mercury. The report found that mercury levels increase with age for all demographic groups, then begin to decline after age 50 (Figure 2). The levels were well below those associated with mercury poisoning. Non-hispanic blacks had the highest blood levels, then Mexican Americans, then non-hispanic whites. I reported on the bioaccumulation of mercury here. Thus, it makes sense that blood levels increase with age. What accounts for the decrease after age 50 and the racial differences? I would put my money on lifestyle differences (where you live, what you do for a living, what you eat), but I don’t really know.
  • Perchlorate was found in the urine of all subjects. Perchlorate is a chemical used to manufacture fireworks, explosives, flares, and rocket propellant. It’s hard to imagine that those uses would make it ubiquitous in the environment, but on the other hand, 14 billion pounds of bombs were dropped by the United States during the Vietnam War alone. This chemical is known to affect thyroid function, but the maximum safe blood level has not yet been determined. This data will help scientists develop standards for safe and unsafe exposure.

I wish I could report on the chemical burden of people living in Missouri, but the CDC data is not broken out by state, and I have not been able to find a report that addresses the issue.

In summary, the report seems to find that environmental chemicals can be widely detected in the blood or urine of Americans. Safe blood levels have been established for some chemicals, and for those the data seem to show that the mean blood level across all significant groups is within the safe level. There may be special populations in which the blood or urine level is higher. Similarly, the number of chemicals tested is a small fraction of those that have been discovered or created, and about most of them, we know very little.


American Chemical Society. 50 Million Unique Chemical Substance Recorded in CAS Registry. Viewed online 4/24/2017 at

Centers for Disease Control and Prevention. Executive Summary, Fourth National Report on Human Exposure to Environmental Chemicals: 2009. National Center for Environmental Health, Division of Laboratory Sciences, Mail Stop F-20, 4770 Buford Highway, NW, Atlanta, GA 30341-3724. Downloaded 4/22/2017 from

Centers for Disease Control and Prevention. Fourth National Report on Human Exposure to Environmental Chemicals: Updated Tables, January 2017, Volumes One and Two.. National Center for Environmental Health, Division of Laboratory Sciences, Mail Stop F-20, 4770 Buford Highway, NW, Atlanta, GA 30341-3724. Downloaded 4/22/2017 from

Centers for Disease Control and Prevention. Executive Summary, Fourth National Report on Human Exposure to Environmental Chemicals: 2009. National Center for Environmental Health, Division of Laboratory Sciences, Mail Stop F-20, 4770 Buford Highway, NW, Atlanta, GA 30341-3724. Downloaded 4/22/2017 from

Clodfelter, Micheal. 1995. Vietnam in Military Statistics: A History of the Indochina Wars, 1792—1991. Jefferson, NC: McFarland & Company. Cited in Wikipedia. List of Bombs Used in the Vietnam War. Viewed online 5/4/2017 at

National Toxicology Program. About NTP. Viewed online 4/24/17 at

New York State Department of Health. Understanding Mercury Exposure Levels. Viewed online 4/24/2017 at

Wikipedia. Iron Poisoning. Viewed online 2/24/2017 at

California Continues to Face Future Water Supply Challenges

Despite the wet winter in 2017, climate change will pose severe challenges to California’s future water supply.

In the last post I reported that Gov. Brown has declared California’s drought emergency officially over. The state has plenty of water for the next year. This post explores the implications of this wet winter for California’s long-term water status.

I first looked at this topic in a 13-post series that ran during the summer of 2015. The series starts here. It contains a lot of information about California’s water supply and consumption. I concluded that at some point in the not-too-distant future California would experience a significant permanent water deficit. The #1 cause of the deficit would be climate change, which is projected to result in a significant reduction in the size of California’s snowcap. The #2 cause would be population increase. I performed the analysis myself because I could find no sources that did anything similar. I’m not going to repeat that analysis in this post. Rather, I’m going to report a couple of new reports that confirm the concerns I had in 2015.

Figure 1. Source: California Dept. of Water Resources.

Figure 1 illustrates the problem California faces. Almost all of California’s precipitation falls during the winter. Some of it gets temporarily “locked up” as snowpack on the Sierra Nevada mountains. Demand for water, however, peaks during the summer. California has many man-made reservoirs that release water during the summer and fall, and the state depends on the melting snowpack to recharge the man-made reservoirs as water is drawn from them. In Figure 1, the blue line represents runoff and the red line represents water demand. You can see that moving the date of maximum runoff earlier in the year increases the amount of water that cannot be captured into storage (yellow area). It has to be dumped; see the post on Oroville Dam to see what happens if the volume of water being dumped gets too high. It increases the amount of water that must be released from storage in the summer and fall. The amount released is now larger than the amount of inflow the reservoir receives, resulting in an increased water deficit (the blue area represents water received, the green area represents water discharged equal to the size of the blue area, and the red area represents the deficit). There is a water deficit in average years, but it is small, and a winter with slightly above average precipitation can make up the deficit. Moving maximum runoff earlier in the year increases the size of the deficit; now only a much wetter year can recharge the reservoirs.

Figure 2. Source: California Dept. of Water Resources.

Figure 2 includes two charts. The first chart shows the percentage of precipitation in California that occurred as rain from 1948-2012. If precipitation occurs as rain, it is not snow and can’t add to the snowpack. On the chart, the black horizontal line is the mean percentage across all years. Red columns represent years with above average percentage of rain, the blue columns below average. There is variation between years, but you can see that the red columns cluster to the right while blue columns cluster to the left. That means that on average an increasing percentage of precipitation is falling as rain. Thus, on average, unless annual precipitation undergoes a sustained increase (which hasn’t happened and is not projected), California’s snowpack will shrink, because what once was snow is now rain.

The second chart in Figure 2 shows runoff measured on the Sacramento River. The red line represents the 50-year period from 1906-1955, while the blue line represents the 52-year period from 1956-2007. This is the specific problem that was discussed conceptually in Figure 1. You can see that runoff has moved earlier in the year by about a month.


Figure 3. Source: National Centers for Environmental Information.

Why is more precipitation falling as rain rather than snow, and why is melt occurring earlier? Because of increased temperature. Winter is when the snow falls in California, and it is when the state receives the bulk of its precipitation. Figure 3 shows that the average winter temperature (December – March) has increased more than 2°F. In addition, if you look at Figure 3 carefully, you can see that the rate of temperature increase accelerated somewhere around 1980. The runoff chart in Figure 2 chunks the data into only 2 groups, each about 50 years long. Because of the acceleration in the increase in temperature, I believe that if they had chunked the data into 3 groups, each about 33 years long, the change towards earlier snowmelt would have been even greater than the one shown.

How dire is the threat is to California’s snowpack? It depends on which climate projection is used. The projected effects of climate change depend very much on how humankind responds to the threat. If we greatly reduce our GHG emissions immediately, the climate will warm less; if we don’t, it will warm more.

Figure 4. Source: California Dept. of Water Resources.

Figure 4 shows the historical size of the California snowpack plus 2 projections. The middle map show the projected size of the snow pack if warming is less. The map on the right shows its size if warming is more. You can see that, even under the low warming scenario, a loss of 48% of the snowpack is projected. Under the high warming scenario, a 65% loss of the snowpack is projected. These projections are for the end of the century. In my original series, I estimated the loss of snowpack at 40% by mid-century. That is not too far off from the high warming scenario. And I have to say, the evidence suggests that so far the world is operating under the high warming scenario, possibly, even worse.

Surface water is not the only source on which California depends. California withdraws significant amounts of water from underground aquifers, especially in (but not limited to) the agricultural areas of the Central Valley. Aquifers can be compared to underground lakes, but don’t think of them as being like a big, hollow cave in which there is a concentrated, pure body of water. Rather, think of them as regions of porous ground, such as gravel or sand. In between the pieces of gravel or sand is space, and that space can hold water. Below and on the sides are rocks or clay that are impervious to water, which allow the water to be held in the aquifer.

So long as the aquifer is charged with water, this is a situation that can last for thousands of years. If, however, water is pumped out without being replaced, then nothing occupies the spaces between the pieces of gravel or sand. If that occurs, the weight of the ground over the aquifer can compress the aquifer, reducing the amount of space available between the pieces of sand and gravel, reducing the capacity of the aquifer to hold water. When this occurs, it sometimes shows up as subsidence on the surface. In California, it is primarily the snowpack that feeds the aquifers. If a significant amount of the snowpack is lost, it will be less able to recharge the aquifers, and they will undergo increased compaction.

Figure 5. Map of Permanent Subsidence. Source: Smith et al, 2016.

As noted in my original series, significant subsidence has already occurred over California’s aquifers. More seems to be occurring every year. A recent study attempted to quantify the amount of water storage capacity being lost to compaction. The study covered the years 2007-2010, so it didn’t even include the recent severe drought (2007, 2008, and 2009 were dry years, but 2010 was 9th wettest in the record). The study covered only a small portion of the south end of the Central Valley Aquifer, yet it found that during those 4 years significant permanent subsidence had occurred (see Figure 5), resulting in a total loss of 748 million cubic meters of water storage, an amount roughly equal to 9% of the groundwater pumping that occurs in the study area. If this ratio held going forward, it would mean that for every 44.4 gallons of water pumped out each year, about 1 gallon of aquifer storage would be lost.

During the recent drought many newspaper articles reported that there had been a sharp increase in the number of wells being drilled in the Central Valley, and that the depth of the wells had also significantly increased. This suggests an increase in the rate at which the water table is being lowered, which would lead to an increased rate of compaction. As the study notes, this is a loss that cannot be replenished; aquifer storage lost to compaction is gone forever.

Dry periods become more devastating when they occur during hot periods. One reason the recent drought in California was so devastating was because it was a hot drought. A recent study found that climate change has already raised the temperature in the state (as in Figure 3 above), and will continue to raise it further, to the point that every dry year is likely to be a hot drought. The report concludes that anthropogenic warming has substantially increased the risk of severe impacts on human and natural systems, such as reduced snowpack, increased wildfire risk, acute water shortages, critical groundwater overdraft, and species extinction.

The bottom line here is that we are talking about the effects of climate change. Climate means average patterns over long periods of time – 30 years at minimum. The current wet period represents only 1 winter. Just as one swallow doesn’t make a summer, so one wet winter doesn’t make a climate trend. For that matter, neither do 5 dry years. However, California’s increase in temperature is a long-term change that does make a climate trend, and every indication suggests it will only increase more.

My conclusion is that this wet winter not withstanding, the concerns I voiced in 2015 over California’s water supply remain valid. As time passes, California will face increasing challenges meeting the demand for water (see here). The state will be unable to secure large new sources of surface water or ground water (see here), and will have to construct large, expensive desalination plants (see here). There will be sufficient water to supply human consumption if it is properly allocated (see here), but water available to agriculture will be reduced, resulting in a decline in California’s agricultural economy (see here). That loss, plus the cost of the desalination plants, will impact California’s economy (see here), as well as the food supply for the entire country.

[In the above paragraph I have referenced several of the posts in my 2015 series Drought in California. If you are interested in the topic, you should read the series sequentially, beginning with Drought in California Part 1: Introduction.]


California Department of Water Resources. 2015. California Climate Science and Data for Water Resources Management. Downloaded 4/6/2017 from

Diffenbaugh, Noah, Daniel Swain, and Danielle Touma. 2015. “Anthropogenic Warming Has Increased Drought Risk in California.” Proceedings of the National Academy of Sciences. Downloaded 3/30/2017 from

National Centers for Environmental Information. “California, Average Temperature, December-March, 1896-2016” Graph generated and downloaded 4/13/2017 at

Smith, R.G., R. Kinght, J. Chen, J.A. Reeves, H.A. Zebker, T. Farr, and Z. Liu. 2016. “Estimating the Permanent Loss of Groundwater Storage in the Southern San Joaquin Valley, California.” Water Resources Research, American Geophysical Union. 10.1002/2016WRO19861. Downloaded 3/30/2017 from

California Drought Emergency Officially Over

Gov. Jerry Brown officially declared California’s drought emergency over on Friday, April 7. It was a fitting ending to one of the worst episodes in California’s drought-laden history.

Or was it? The next two posts update California’s water situation. This one focuses on the current short-term situation. The next one focuses on the future, with an eye toward the future impact of climate change. I have personal reasons for following California’s water situation – I have family living there. But in addition, California is the most populous state in the Union, it has the largest economy of any state, and the state grows a ridiculously large fraction of our food. What happens in California affects us here in Missouri.

Figure 1. California Snowpack, 3/31/2017. Source: California Department of Water Resources.

Is the short-term drought truly over? Yes, I think so. The vast majority of California’s precipitation falls during the winter, and the snowpack that builds up in the Sierra Nevada Mountains serves as California’s largest “reservoir.” As it melts, it not only releases water that represents about 30% of the state’s water supply, but it also feeds water into the underground aquifers that provide groundwater to much of the state. Thus, the size of the snowpack is the most important factor in determining California’s water status. California measures the water content of the snowpack electronically and manually. The measurements around April 1 are considered the most important, as that is when the snowpack is typically at its largest. Figure 1 shows the report for this year. Statewide, the water content of the snowpack was 164% of average for the date, almost 2/3 larger than average. The water content was significantly above average in all three regions of the snowpack, North, Central, and South.



I follow the snow report at Mammoth Mountain Ski Resort to provide a specific example of the snow conditions. Figure 2 shows that through March, Mammoth received over 500 inches of snow, one of the highest totals in the record going back to 1969-70. The column for 2016-17 has very large blue and orange sections, indicating that the majority of the snow fell in January and February. Figure 3 confirms the impression. It charts the amount of snowfall at Mammoth during each month of the 2016-17 snow season, and compares it to the average for that month across all years. You can see that both January and February were monster snow months, especially January. By March, snowfall had already fallen below average. I wouldn’t make too much of this fact, one month doesn’t make a trend.

Figure 2. Source: Mammoth Mountain Ski Resort.

Figure 3. Data source: Mammoth Mountain Ski Resort.











Figure 4. Source: California Data Exchange Center.

California also stores water in man-made reservoirs. Figure 4 show the condition of 12 especially important ones on March 31. Most were above their historical average for that date, and many were approaching their maximum capacity. Those who follow this blog know that the Oroville Reservoir actually received so much water that it damaged both the main and emergency spillways, threatening collapse of the dam and requiring evacuation of thousands of people down stream. (See here.)







Figure 5. Elevation of the Surface of Lake Mead. Source:

In addition, Southern California receives the lion’s share of water drawn from the Colorado River, thus the status of Lake Mead, the largest reservoir on the Colorado, is important to the state. A study in 2008 found that there was a 50% chance the reservoir would go dry by 2021. On March 31, Lake Mead was at 1088.26 feet above sea level. (This doesn’t mean there were that many feet of water in the reservoir, Hoover Dam isn’t that tall. Rather, it represents how many feet above sea level the surface of the water was. Lake Mead’s maximum depth is 532 feet.) The current level represents 41.38% of capacity. Figure 5 shows the level of the lake over time. You can see that the line tends to go up with the spring snowmelt, and down during the rest of the year. This year it is up very slightly year-over-year, but the trend has been relentlessly down since 2000.

The conclusion seems inescapable: for this year at least, California has plenty of water. The short-term drought is over. One year doesn’t make a climate trend, however. In the next post I will consider the implications of this wet winter for California’s water situation going into the future.


Barnett, Tim, and David Pierce. 2008. “When Will Lake Mead Go Dry?” Water Resources Research, 44, W03201. Retrieved online at

CA.GOV. Governor Brown Lifts Drought Emergency, Retains Prohibition on Wasteful Practices. Viewed online 4/10/2017 at

California Data Exchange Center. Conditions for Major Reservoirs: 31-Mar-2017. Viewed online at

California Department of Water Resources. Snow Water Equivalents (inches) for 3/30/2017. Viewed online 3/31/2017 at

Mammoth Mountain Ski Resort. Snow Conditions and Weather, Extended Snow History. Data downloaded 4/2/2017 from “Lake Mead Daily Lake Levels.” Downloaded 4/5/2017 from

Ozone Was the Most Important Air Pollutant in Missouri in 2016

Ozone was the most important air pollutant in Missouri on more days than any other. It increased its “lead” over PM2.5, which was second.

The Air Quality Index is a measure that combines the level of pollution from six criterion pollutants: ozone (O3), sulfur dioxide (SO2), nitrous oxide (NO2), carbon monoxide (CO), particulate matter smaller than 2.5 micrometers (PM2.5), and particulate matter between 2.5 and 10 micrometers (PM10). For a brief discussion of these pollutants, see Air Quality Update 2016.

Figure 1. Data source: Environmental Protection Agency.

Figure 1 shows the percentage of days for which each of the criterion pollutants was the most important one. The chart combines all 20 counties together. Since 2009 ozone has been the most important pollutant on more days than any of the other pollutants, and it extended its “lead” in 2016. PM2.5 was the most important pollutant on the second highest number of days. Since 2007, however, the percentage of days on which it was the most important pollutant has been trending lower. One or the other of these two pollutants was the most important on 85% of all days statewide.

Thirty years ago, ozone was a much less important pollutant than it is now. In 1983, it was the most important pollutant on fewer than 30% of the days statewide, but in 2016 it was the most important pollutant on 54% of the days. While we need ozone in the upper atmosphere to shield us from ultraviolet radiation, at ground level it is a strongly corrosive gas that is harmful to plants and animals (including us humans). We don’t emit it directly into the air. Rather, it is created when nitrogen oxides and volatile organic compounds (vapor from gasoline and other similar liquids) react in the presence of sunlight. These pollutants are emitted into the atmosphere by industrial facilities, electric power plants, and motor vehicles.

The second most important pollutant was PM2.5 (31% of days in 2016). These tiny particles were not recognized as dangerous until relatively recently, though now they are thought to be the most deadly form of air pollution. I can’t find anything that says so specifically, but I believe the zero readings in 1983 and 1993 means that PM2.5 wasn’t being measured in Missouri, not that it wasn’t a significant pollutant back then. The EPA significantly tightened its regulations for PM2.5 in 2012. In 2015, no Missouri county was determined to be noncompliant with the new standards, however data gaps from sensors just across the Mississippi River prevented determination of whether pollution from Missouri was causing a violation of standards in the Illinois side of the metro area. Thus, the counties of Franklin, Jefferson, St. Charles, St. Louis, and St. Louis City were all called “unclassified.” Road vehicles, industrial emissions, power plants, and fires are important sources of PM2.5.

Sulfur dioxide used to be by far the most important pollutant. While it has not been eliminated and was still the most important pollutant on some days, good progress has been made on reducing SO2 emissions (9% of days in 2016). For the role of SO2 in background air pollution, see this post.

Don’t forget that Figure 1 does not show the levels of the six pollutants, it only shows the number of days on which each was the most important. As previous posts have clearly shown, air quality is better. As we have reduced some types of air pollution, apparently, other types have become more important.

Missouri has come a long way in improving its air quality. To a large extent, it did so in two ways: by kicking some of its coal habit (replacing coal with natural gas and oil as sources of energy), and by requiring large industrial emitters to install pollution control equipment. We have more work to do, especially with regard to ozone and PM2.5, but it has been a significant environmental success story.


Environmental Protection Agency. Air Quality Index Report. This is a data portal operated by the EPA. Data for 2014, Missouri, and grouped by County downloaded on 11/6/2015 from

Missouri Department of Natural Resources. Missouri State Implementation Plan: Infrastructure Elements for the 2012 Annual PM2.5 Standard. Viewed online 3/30/2017 at

Few Unhealthy Air Days in Missouri Counties

Figure 1. Data source: Environmental Protection Agency.

In the previous post, I reported on the percentage of days during which air quality was in the good range in 20 Missouri counties. It is one thing to ask whether a county’s air quality is good, and another to ask if it is so bad that it is unhealthy. This post focuses on the percentage of days with unhealthy air quality.

I looked at data from the EPA’s Air Quality System Data Mart for 20 Missouri counties. The data covered the years 2003-2016, plus the years 1983 and 1993 for a longer term perspective. For a fuller discussion of air quality and the data used for this post, and a map of the 20 counties, see my post Air Quality Update, 2016.

The EPA data distinguishes 4 levels of unhealthy air: Unhealthy for Sensitive Individuals, Unhealthy, Very Unhealthy, and Hazardous. No Missouri county was reported to have Very Unhealthy or Hazardous air quality for any of the years I studied. Figure 1 shows the percentage of monitored days for which air quality was either Unhealthy for Sensitive Individuals, or Unhealthy. The top chart shows a group of counties along the Mississippi River north or south of St. Louis. The middle chart shows a group of counties in the Kansas City-St. Joseph region. The bottom chart shows a group of widely dispersed counties outside of the other two areas.

(Click on chart for larger view).

The percentage of unhealthy air days was 3% or below for all Missouri counties . There were no unhealthy air days at all in 12 of the 20 counties. Compared to 2014, two counties in the Mississippi region and one in the Kansas City region showed very small increases (St. Charles, Jefferson, and Stoddard Counties). Jackson County showed a significant decrease and the City of St. Louis showed a very small decrease. The other counties all stayed the same.

It is heartening, and good for the lungs too, that no county in Missouri had a significant fraction of days on which the air quality was unhealthy. The state clearly has improved its air quality.


Environmental Protection Agency. Air Quality Index Report. This is a data portal operated by the EPA. Data downloaded on 3/23/2017 from